A known braking control apparatus disclosed in JP2001-71755A includes a circulation conduit trough which a partial amount of brake fluid discharged from a pump is circulated back to the pump by means of rotations of a motor (i.e., by means of a motor driven to rotate). The partial amount of brake fluid discharged from the pump is circulated back to the pump without being supplied to a wheel cylinder. A pressure regulating valve is provided at the circulation conduit to adjust a pressure difference between an upstream side and a downstream side of the pressure regulating valve. Specifically, a correlation between the pressure difference and an applied current to the pressure regulating valve is provided to be used for obtaining the pressure difference on the basis of which an appropriate current is applied to the pressure regulating valve. Accordingly, the wheel cylinder pressure is controlled by the adjustment of the pressure difference.
According to the aforementioned braking control apparatus, an amount of fluid circulated back to the pump is not changed because the motor rotates at a predetermined constant speed to drive the pump. However, in a case where a rotational speed of the motor changes when driving the pump, the amount of fluid circulated back to the pump changes, which may decrease an accuracy for controlling the wheel cylinder pressure.
A need thus exists for a braking control apparatus which is not susceptible to the drawback mentioned above.